State in components that are removed are never dropped

[ealmloff]

Problem

The state create in use_state hooks in components that are created and then removed are never have there drop handler called.

Steps To Reproduce

Run:

use dioxus::prelude::*;

fn main() {
    dioxus_desktop::launch(app);
}

fn app(cx: Scope) -> Element {
    let count = if cx.generation() % 2 == 0 { 10 } else { 0 };
    if cx.generation() < 10 {
        cx.needs_update();
    }

    render! {
        (0..count).map(|_| rsx!{
            Comp {}
        })
    }
}

fn Comp(cx: Scope) -> Element {
    cx.use_hook(|| Drops);
    render! {
        div{}
    }
}

struct Drops;

impl Drop for Drops {
    fn drop(&mut self) {
        println!("Dropped!");
    }
}

Expected behavior

The message Dropped should be called when the program starts, not just when it is closed and the VirtualDom is dropped

Environment:

• Dioxus version: [e.g. v0.17, master]
• Rust version: 1.66.0
• OS info: Windows
• App platform: core

Questionnaire

• [x] #770
• [ ] I would like to fix and I have a solution
• [x] I don't have time to fix this right now, but maybe later

[ealmloff]

It looks like drop_scope is never called in remove_component here: https://github.com/DioxusLabs/dioxus/blob/master/packages/core/src/diff.rs#L918

[jkelleyrtp]

Good catch, yep, the "remove component node" function should just be returning the props from the scope to the vcomponent in case the vcomponent gets rendered again.

[jkelleyrtp]

Put up #771

[ealmloff]

fixed in #771